Apply the distributive property to factor out the greatest common factor. $20+4k =$
Answer: $ 4$ is the greatest common factor of $20$ and $4k$. $\phantom{=}20+4k $ $={4}\cdot 5+{4}\cdot k$ $={4}(5+k)~~~~~~~~$ Apply the distributive property. The answer: $ {4}(5+k) $